Why are shorter MTB cranks suddenly all the rage?
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- čas přidán 16. 05. 2024
- "I'm thinking about getting longer cranks", said no one in 2023. It's definitely true that shorter cranks are a trend right now, but why? Is it all nonsense, or is there something to it? Today we'll take a deep dive into crank length and how it affects your performance. You'll get a highly biased take on the subject from someone with very short legs.
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Seth I wanted to compliment you on something you’ve probably heard before but I don’t see often in the comments. That is your script writing skills. The words flow effortlessly and the information is delivered succinctly but with enough color to give me entertainment. And also there the delivery and how you speak to the camera. I know it probably took lots of effort but you sound so natural and relaxed. Kudos to you!
That's something I always liked but couldn't pinpoint until YOUR articulate delivery!
He used to write is whole script in the description earlier. It was then I realised the work he put in the script before making the video. It's the reason is delivery feels so effortless.
the script + enjoyable voice is his secret to his follower amounts ;)
Good prepwork makes easy work.
Yeah, I really noticed it in this video. Many of his other recent scripted videos are really kicking it up in the quality too.
I'm so glad crank length is FINALLY being addressed! Even 15+ years ago it was frustrating to me seeing size medium & even small bikes being sold with 175mm cranks
I like it. Keeps the feet close to centre. Easier to whip 💪
As Seth points out, it has now gone the other way. As a tall rider I am now seeing L and XL bikes with 170mm cranks. When I've ridden 175mm my whole life with no issues why would I want to lose leverage power? Interesting video.
@@rouxenophobeContador probably thought the same thing before Froome ripped past him spinning while sitting down like a madman up Ventoux.
It has been addressed many times - most people have been too lazy to not pay attention and ride what they got. You could have always swapped cranks out whenever you wanted. Heck 20 years ago the standard was 165-170 - i had a hard time finding 175 as i have long legs. Now it's common place. The bike industry just takes what is old and had tons of info about and tries to spin it as some new discovery. Goes in circles.
Yeah. I had a tough time finding new cranks. Went from 175 to 165. It was a huge improvement. The idea that you "lose leverage" is misunderstood since having smaller cranks keeps your legs at a smaller angle and keeps them more in their power range and, since the gear ratio is the same, no loss of top end either. I would have gone to a 160 if I could have found one at the time, but even the 165 was easier on my back than the 175 so no regrets.
Man, your ability to create a video is insane man. The storytelling, the filming, the editing, and - most importantly - conveying the message... Dude. It's really good.
It's not a coincidence that he has over 2.5 million subscribers.
and the number one mtb blogger on youtube. @@jasper_of_puppets
Dude man. Dude. Man.
The videos from two years ago were so much better than these videos 😢😮😮😢
This is an important issue for me. Like you, I'm short. I'm also in the "older" category, and have dicey knees. I've watched several "crank length" videos, and this was one of the best. Thank you!
I never considered shorter cranks until I talked with a professional about my hip pain. It was suggested I use shorter cranks, so I did and now no more hip issues. No more rock strikes is a bonus as well
Variation is probably the answer. I have been riding 56 years, I am 66 years old, I have to make modifications to my position on the bike all the time to keep riding. I have 3 road bikes today all with different saddles, handlebar widths, seat heights, seat fore/aft adjustments, handlebar heights and stem lengths, crankarm length. Every four days I am on a different bike with a new position. I ride off-road too, so that is where the fourth bike comes in. I also weight train and hike for muscle balance. I also have four main pedal strokes and a variable cadence from 80 to 110. All of this combines to take overuse stress off the specific parts of the body.
@@WildernessMusic_GentleSerene Very true
@@WildernessMusic_GentleSerene No… shorter cranks open up the hip angle when you’re pedalling, which means less stress on the hips, because it’s a smaller circle you’re turning.
No to what? There is not one simple answer to fitness, health and strength balance. Shorter cranks also place higher stress on the knees. Plus we need to talk about 100 items on this list such as seat height, seat for/aft adjustment, seat angle, placement of feet over the pedal spindle, reach to handlebars, size of frame, cadence, skills of pedal strokes....and 92 others....@@benoosthuizen4961
Definitely not for xc racing
This was much more informative than any of the other videos or articles I’ve seen.
I love the shorter crank move, especially on a ebike.
Seth is in the groove with videos, has been for some time. He’s a pillar for the community now and I am happy about that…such a good dude. I feel fortunate that he makes the content he makes, it checks all boxes for me.
Merry Christmas 🎄
I've only got a 29.5" inseam and always found my knees started to hurt when cycling for a long time seated on my road bike. Shifting to my 162.5mm cranks I have now completely eliminated the pain overnight - it's "only" 10mm shorter but you get the benefit at the top and bottom of the pedal stroke so it's actually more like 20mm
After like 3-4 month break from this, mostly coz of lot of work and hospital visits, it's nice to come back and watch everything I missed. Seth's channels always get me into chill mood, almost feeling the forests breeze and fresh air. Can't wait for better weather and stitches to heal and go back to training mtb
Love your videos.
I had heard the term "making circles with your feet" and it never made sense to me. I always felt like I was stair-climbing on any bicycle I rode for as long as I can remember.
In the last year I learned about shorter crank lengths for shorter inseams. Several methods I used recommended cranks from 150mm to 165mm. I ended up ordering 165 because they were readily available. Changing my from 175mm to 165mm on one of my bikes may not sound like much but it was mind blowing. In the end it didn't change how many watts I could put out, but it did change /how/. I earnestly believed it was going to be a minor change - I was wrong it was a major change.
I wish I understood how much it was going to change things, because I would have been a little more specific about apples to apples testing the same routes before and after.
Some of the things I did notice with concrete certainty:
* My whole body moved a lot less. As you mentioned in the video.
* Also as you mentioned, I made up for raw power by pedaling faster
* I could pedal a LOT faster before I spun out. (In part because my motion was localized to my legs and not whole body). Before I'd start maxing out around 80rpm and could push to 90 for short sprints, any faster I felt like I was flying off the pedals. Now I am comfortable at around 80, often push to 90, and have reached 110rpm on more than one occasion, but feel like I rarely need to ever pedal that fast.
Some things I wish I tested more formally but show marginal gains with data:
* Longer hill climbs seem easier, and my time appeared to have dropped slightly
* My overall endurance seems to have gone up, but at the time of the swap I did not have any longer trips to back it up.
Sometime in the spring I will have time to do something like a 2x centuries with hills and recovery time in between to make them equal tests. I'll swap my cranks between the two and collect all my data from the test. Won't be pure science as it won't account for differences in weather, variations in my physical state, etc, but I think it will show enough differences to suggest changing to shorter cranks is absolutely worth the experimentation.
At the very least, I have experienced the feeling of making circles with my feet for the first time in 40ish years. It feels awesome.
You’re awesome. Thanks for sharing this information, instead of keeping it to yourself. At least one guy appreciates you, because this is the kind of info i look for in the comments.
Try this, just ride on flat ground at a comfortable cruising speed. Not fast! Check your speed. Then ... just think of peddling in circles but don't increase your cadence. You will notice a speed increase. It is amazing. Also, think of pawing like a bull, especially if you need more power like on an incline. I always remember being amazed when I first did that as directed by my coach back in the 1980s. I think it is telling and pretty cool.
So helpful! Thank you for this. I'm always trying to think what are the most impactful upgrades I should consider, and this one seems like it may be a top choice for me now. Keep up the great work and content.
Great video. My buddies have been talking about this. Thanks for showing us the crank length rental kit. I'll pass that on to my group.
I'm 5'3" and I've been loving my 160 cranks for almost 2 years. 😊 Wishing I could find a set for my fat bike too. Recently settled with 165mm for the fat bike but fingers crossed shorter cranks keep gaining popularity 🤞
i was born and raised on 175mm cranks (25+ years). i recently switched to 165mm, i can't say that i was blown away, at first. in fact i had to reluctantly stick with it and give them a shot. technical climbing is my favorite thing to do on a bike and not having that extra leverage was a little sad at first. i've just learned to deal with it, but also i'm enjoying fewer pedal strikes. Note: i'm 6ft and have long legs and short torso.
Seth, great video. I just purchased a set for my hardtail as it is my guinea pig. You are the voice of reason, keep up the good work.
Just watch a bunch of your video makes me want to ride and fix my old bike again. Hope u still make this kind of content and have a good day🎉
Love the way Seth can laugh at himself! Humility bro! 👊🏼
I had just purchased a set of 155 cranks for my E-bike before watching your video, my justification is - SAFETY!!! My last crash was near the end of a long ride on an an easy section of trail, I was tired and my uphill pedal was hanging a little low as I was coasting along, I didn't notice a little half rotted 6 inch stump that caught my pedal and sent me over hard! Shorter cranks and it would have been a perfect ride.
I really enjoy your videos. I’ve been riding 165 on my road and mountain bikes. My wife rides 160’s on her road and mountain bike as well. Made a huge difference for us. Keep on rocking the great videos.
Thanks for making a video about this! I actually confronted this two years ago, when I bought a bike that was too big for me and couldn’t get the seat post to drop low enough: 165mm cranks did the trick!
Yep, I would be 187mm cranks but love my 170'S. I do have a 240mm dropper to help out too! Spinning a 30 tooth chain ring to help get my 280+pound arss to the top of our hills. Great work as always!!!
I'm 6'2" and went from 175mm to 165mm. Huge improvement. Significantly decreased pedal strikes and really wasn't a noticeable change in leverage. That combined with an oval chainring really helped my climbing.
What's your bike? What size of a chainring have you bought? I am about to buy one 32t egg-ring for my 30t trance 27.5 L but the clearance is going to be really tight. Do you have any issues with it? Cheers!
Yep, I'm 6'1 and have 165mm cranks on all my bikes.
Been doing it for years
Yep, I'm similar 6' and 165mm is my jam. Based on Seths box measurement I am 164, so spot on.
The leverage issue is a bigger deal when you're pushing an 11-30 T cassette with a 42/52 T chainring on a road bike. On my MTB, I'm only asking a 30T to work across an 11-50 cog so I always can just drop a gear and at 30:50 5mm more leverage isn't going to make/break me. Rock hits on the other hand can stop me in my tracks.
+1 for 6'2" running 165's
Been looking to shorten my cranks for sometime. Now I have a way to get a starting point. I know the 170s on my bike currently are too long. Thanks Seth!!!
Thanks Seth, I keep learning cool things every time you post!!
Really appreciate this video! Girlfriend is short (5'0) and has often complained of hip discomfort. She has been on 170mm cranks, as that's what came with her 'small' bike. Suboptimal! Glad more manufacturers are looking into this - hopefully somebody brings a budget option to market.
You could have always bought shorter cranks - they have always existed.
I've been running Canfield 155mm on my Ripmo AF for the last year, reduced chainring size and almost zero downsides.
I also didn't go shorter because it "seemed crazy" but would happily try 150mm now.
Budget option? They're just cranks, just buy shorter cranks. Cheap cranks are literally everywhere and always have been.
I replaced my partners 170's with a set of 152 off a kids bike and it fixed her knee discomfort within a ride or two. It also increased her normal riding speed. If your bottom bracket is square taper then a set of kids cranks is probably the cheapest way to try it out, if you can find a set. The main bike shop near me has 170 on the kids bikes, which must be horrible for them to ride
Im 170cm and Im using 152 cranks as well. Bike shop put big ones on kid' bikes cause adults are buying them, presumably in Southeast Asia. Or they are blithering idiots. @@sew2000
My Giant Trance E+ size L came with the shortest cranks on any bike I have (165mm) and I'm liking them for that application. At 6' with the inseam of a typical 6'4" person I have typically been good with 175 on mountain/road/cyclocross bikes and my bmx bikes have 180mm.
A good shop that does proper fitting can really help work out strange body geometry issues that may affect other fitment areas on the bike.
It's been a while since I watched one of your videos, and I truly forgot how awesome you really are.
Keep it up.
The quality on these videos is truly amazing, congrats.
Great video as usual!
I switched to 165mm cranks when I found some that fit my bike about 7 years ago, and it was such a game-changer! I was always a lugger pushing heavy gears (I now need a new knee! ). But with the 165mm I could instantly spin faster and more naturally. Attempting to spin with longer cranks always bugged my hips. Plus, I could stand easier and crank for sudden bursts and sprinting, something I never liked doing as a long-crank lugger. What's more, and conversely, I could sit much lower too with the dropper lower and spin and use my quads more, which I never liked doing with 175mm cranks. It opened up the range at both ends, sitting high or low with the dropper. So I'd love to try 150mm cranks!
Here's an experiment: Go to the gym, find the leg press machine., and try to squat the full stack; (forget it!) But with the same weight, start from a much higher position, with your legs already extended. Though you're not moving it far, you can press that same massive weight all day. The shorter cranks, while in a super high position, allow you to put out some major power with legs at a fuller extension.
Mechanically and according to the laws of physics, there's not much difference as you make adjustments with cadence and power. But for some positions, and to be more versatile, (and possibly bio-mechanically), I reckon the shorter cranks give you more options. You also have more clearance, of course. To me, the only downside that your highest dropper position will be even higher than before, (equal to the difference in the length of the crank arm). But generally, that would only be for road and flat trail, as you'd be sitting lower and spinning more with the shorter crank on MTB terrain.
I hadn't thought of that crank/dropper relationship. My dropper is about 5mm too tall so shortening my crank (which I want to do anyway), raising the bottom-dead-center will be perfect!
I'm considering going from 170s to 165s on my XL Ripmo due to pedal strikes and knee issues when the seat is lower than optimal. Did you modify the sprocket as well?
I have found exactly the opposite. Longer cranks mean less force is required at the same cadence and power output. Bio-mechanically, it takes a certain amount of time for muscles to contract, and it's going to take a larger/longer muscle more range of motion to develop the power.
Using your leg-press example, keep your legs almost straight, and you can probably move 1000lbs, but that means it's 1000lbs of force on your knees.
if you instead move 100lbs 10x as far in the same time, you're doing just as much work, but the load on your knees is much lower.
It's all about getting it well matched. too short is bad, too long is bad. Ideal will vary by person, especially with leg length.
If you're on the short side, shorter cranks will be a big improvement. If you're on the tall side, you're probably already using too-short cranks, and going shorter is just further compromising that.
this is a good place to mention that the sheldon brown bicycle gear calculator has provisions for crank length. if you use “gain ratios” you can compare gearing across different crank lengths.
For me, i specced my steamroller with 165mm cranks for better clearance and higher cadence. I’m quite used to spinning shorter cranks as a unicyclist. My Muni setup is on either 125 or 150mm cranks and my 36er is on 110mm cranks unless i’m riding it off road. I don’t know if i’ll invest in shorter cranks on my MTB, but i welcome the shift
RIP to the legend...
Munis are set up this way because of lack of gearing, not for "optimal" leverage or power.
@@dudeonbike800 sort of. MUnis are set up for “optimal” leverage in that you want to use the shortest length that still gives enough control to climb hills and get over rocks and roots. i don’t think anyone ought to go as short as 110mm on a bike, but 150mm cranks generally feel better to me than anything in the normal range 165-175mm. When you get really short, the short stroke length becomes a problem, but at more moderate lengths i think there are a few situational advantages to the shorter cranks
@@unitimmy That's not really "optimal", it's just trading off one very sub-optimal factor for another to try and keep any of them from getting completely unusable.
On my muni, I prefer longer cranks, even though it's limiting my top speed, and worse for pedal strikes, it does give me a lot more control when riding down rock gardens, and just better suits my riding. I've got short cranks on my freestyle unicycles, but it's purely for speed reasons. Again, very sub-optimal from a leverage/ergonomics standpoint, just to allow a ridiculously high cadence to partially compensate for ridiculously low gearing.
Always entertaining buddy have a great time to finish the year out looking forward to next years content
Crank length is a huge issue with bike fit. I first slid down this rabit hole while I was fitting my kids on mountain bikes, surprise yes most kids mtb come with too long cranks. I noticed when I put my 3yr old son's seat down for proper leg extension and when he pedalled his knee would come above his hip. This caused him to shift his hips back and forth while pedalling, resulting in poor balance adn bad spinning. Being a proper MTB dad I sourced shorter cranks and have been putting shorter cranks on all new kids bikes. Most kids bikes use square taper BB axle and there are more selection, although heavier. It's great to see more options of shorter cranks with proper hollow thru axles. Thank-you Seth for making this more aware to the community.
go crankless
I recently dropped down to 170mm cranks from 175mm on most of my bikes, BMX bike excluded. I am going to try 165mm, but that will be my limit as I do want a certain degree of leverage. I don't always pedal in circles, when things get technical I do the ratchet method to prevent pedal strikes and I have gotten really good at it over the many decades of riding. So that leverage when ratcheting at low speed to get up and over something or through a technical rock garden or other feature is essential to me. It's all about finding that balance between leverage and spinability.
Yep, I learned something and also reinforced what I was already thinking. I went for shorter cranks earlier this year and felt an immediate improvement 👍
We purchased a folding bike months ago and I noticed immediately its crank length (19.5cm), it actually felt good on hills initially. But you notice the extra work your knees are doing after a while. Its also hilarious fun trying to ride up steeper hills as it pops wheelies even whilst hanging over the handlebars.
Dang, I never really thought about crank length but now I'm wondering if I should look into changing mine. I'm around your height and working on rehabbing my knee with an e-bike. If shorter cranks could reduce the stress on my knees that would be a game changer!
Yes you should. Absolutely. Don't you know the bike industry is in a major financial crisis right now? It's your duty to buy into the latest marketing plan.
@@dudeonbike800 Haha, I doubt buying some cheap cranks on Amazon is the windfall the bike industry is hoping for.
Do it!
When I moved from the 175 cranks installed to 160 or 165 on my bikes, my knee and hip joint pain almost completely disappeared (at most feeling a little tired in the knees versus stiff or sprained and my hips don’t hurt at all) and I’ve no loss in climbing power as my knees remain in a better range of motion for exerting force.
One thing I didn’t anticipate is it also eliminated lower back pain just above the pelvis. Apparently I was rolling my hips a lot with the commonly-used 175 cranks, but don’t do it to the point of pain with the shorter cranks.
165 cranks, slim pedals, and oval chainring made such a difference for me. More clearance from pedal strikes, less side to side body movement while pedaling, and slower cadence to help time crank ratcheting.
Hi Seth! I love your videos they are super informative and you are a wonderful teacher!!! Thanks for doing these! 😊
Great video on a great topic. I'm 5'-10" and while that is an average height for men, I've got short legs and a long body. I came across Appleman's website and changed to 165mm cranks based on some leg length formulas and feel better. You are right that we obsess about all other points of fit, but we all use the same crank length. I love that this topic is getting attention now.
At 6'1(ish) with a 32" inseam, I switched from 175 to 165 years back to solve rock strike issues riding in Austin TX and never looked back. All the concerns I had about spinning out or feeling like I was riding a kids bike were total non-issues. This is a trend I am 1000% onboard with.
@enriqueamaya3883Are you on your knees for Jesus so he can fill you up with his love? Do you feel him deep inside you?
Excellent topic and great explanation. I do want to point out something that you missed. The slightly higher saddle height should be irrelevant because when you size bikes, you should first select the correct crank size, then adjust seat height (if you can’t reach the ground you should be downsizing to 27.5 wheels). This is something I learned in road biking when adjusting my road bike to my body type. So, if you have excessively long crank arms but slightly lower saddle, you will experience more unwanted hip motion and if left unaddressed, injury. So, having a slightly higher seat high due to correctly sized cranks is ALWAYS a good tradeoff.
Professor Seth thanks for sharing with us today and we will see you next time!!
Life changing! Thank you Seth!
When I built my Intense with NOS parts 9 years ago I got 175mm XT cranks for a deal and didn’t think twice about at 5’9”… This year I went eagle with 165 and was very happy with the change. Now I’m looking at the 172.5 on my road bike wondering….
Kerp in mind, reducing pedal strikes is one of the biggest positive of short cranks. On a road bike it's more about ergonomics and bike fit, so there's less reason to swap. If you're serious about it, Dylan Johnson has made some very in-depth videos examining studies about changing crank length.
I'm 5'9 and I switched to 165mm on my road bike, they feel great. All the discomfort in the knees is gone, I finally feel at home.
I also switched to smaller chainrings, 46/34, and to a slightly bigger cassette 11-32. It's a randonneuring bike, so I'd rather have more mid range than higher top speed.
5.9 as well, but have always liked 170
Merry Christmas Seth. Recently purchased new bike with 175mm cranks. I was going to drill and tap 2 new holes for 145mm and 160mm, but only had room for 1 hole so I split the difference and went with 155mm. Only spent about $50 dollars on drill bits and taps. Best decision ever, works so much better. God bless you.
Hey Seth, I love your videos and you have inspired me to make a mountain bike trail of my own in my backyard
I always learn something from your vids! Thanks!
Yeah, I’m convinced now, ever since I bought a Stumpjumper size M, which came with 175mm cranks, I’ve been hitting rocks on technical climbs like I’ve never have. I’m only 176cm tall and my inseam seems about 80cm, so I’d need 160mm cranks. But I’m going with 165mm cranks I think. It’ll get me 1cm more ground clearance and I believe my 170mm dropper is actually a bit to long for me, at full extension, so that’ll be fixed as well.
I was curious about my stumpy, it's a S3 (M) and came with 170mm but 165 does look tempting
keep in mind every bike has a different bottom bracket height... your bike may also be lower which would cause more pedal strikes
The dropping the saddle bit to simulate the shorter pedal stroke is kinda missing one of the biggest advantages of going shorter on the cranks. For us short kings the hip angle that results from a long crank and our body morphology means a really tight hip angle at Top Dead Center, which I'm starting to realize is making my hips permanently tighter. Glad you mentioned the 5dev's. I'll have to give them a look! 😊
Glad the channel is back in my algorithm!❤
I’ve been riding with Canfield 160mm cranks for a couple of years now. Love them. And they are way cheaper than any other option.
Appreciate the tip! Those are definitely cheaper than other options. May have to score a set for my girlfriend's bike!
Are they compatible with SRAM GX ?
@@awfully.averageyes sir! They actually use SRAM style chainrings too, so if you already have one you can keep it.
@@nobodycaresMTB oh that's great to know !
I predict we’re going to start seeing lower BB bikes in the next year or two intended for shorter cranks, so the seat stays in the same position. This’ll be the new “welp, I have to throw my 3-old bike away now” improvement.
People who stick with their old bike instead of chasing trends usually seem happier
This, like kale and skinny jeans, is just a dumb fad that'll be gone in a matter of a couple years. He literally told you the exact words in his scripted speech...it's more efficient to go with longer crank arms. The VAST majority of the biking market isn't going the way of smaller crank arms. It's only the niche that likes catering to the dummies that like to pay 10x what they really should on parts.
I’d like to keep where we at now. I go on our local single track trails with lots of roots and logs so a good BB height clearance is requires,just shorter cranks will do hehe
Almost no one who suddenly cares about ground clearance knows what their current BB height is anyway. You are right though, the whole industry is designed around selling a 'bike" as a single product and avoiding anyone building one part by part.
I'm confused by this, so maybe you can explain it. We haven't moved the BB (as yet), we've just put shorter cranks on it. Therefore wouldn't the maximum pedal position be _lower_ and therefore you would have your saddle lower in order to achieve the same knee bend angle at the top of your stroke?
Always informative and entertaining Seth! Happy holidays!
Great video man, I appreciate the help. Thanks!
super interesting! I've always wondered why no bike company is changing the status quo, in mountain Unicycling, crank size is the most important value! we run cranks between 117mm and 135mm
so eventually we can use some 5dev in the future too 🤤
Thanks for this video, Seth. I'm 5'6" with a 29.5 inseam and switched one bike from 175s to 165s and the other from 170s to 165s and it was worth every dollar. The video names some of the things I considered and others I did not. With this in mind, I am working on an old Trek 800 13" frame for my daughter who is quickly outgrowing her current 24" bike. I'm looking to source cranks and options are limted. Have you considered doing a smaller 26" rigid build for kids? I'm curious what you could find.
I am the same height, same inseam. Going to 165's from 170's has made some difference. I get it that some leverage is lost. But with 11/12 speed cassettes with close gearing, this is not an issue, as leverage is countered by torque from smaller gearing. But more importantly, my knees. While they don't hurt on 170s, I can feel some stress on them. With 165s, this the stress on my knees is reduced. I can feel it.
So far, of my bikes, three are using 165s. I'm will be changing to 165s for all but my classics (where I still use the original components, but I don't ride these daily)
That is something I think is going to make a huge difference for me. Thx for the lesson.
Merry Christmas from Canada! 🎉. Great vids!
Hey Seth, maybe a fun topic to talk about (not sure it will fill a full video though). Bike sizing charts often use a rider's height. However, some people have long legs and a short torso, while others mighr have short legs and a long torso (like me). I prefer to opt for the larger size when I am between sizes, while someone with long legs probably benefits from the smaller size since their reach from the hips to the handlebars is shorter. I don't know if there's any science to this, but it's worth considering. Also lines up with the inseam measurements from this video regarding crank length.
Lots of boutique bike brands use pubic bone height, which is a fairly accurate way to measure the length of your legs. Seth demonstrates how to measure it at the end of the video.
Fully agree that this would be an interesting topic.
I am exactly that kind of "odd geometry" person: I am 192cm/ 6 foot 3.6inch, but I have an inseam of only 87cm/2 foot 10,25 inches.
When recently shopping for a new bike, the frame size calculators of different manufacturers would usually spit out either size L (if they prioritized inseam) or XL (if they prioritized or only considered total body height). When you then compared the actual true bike geometry of the different manufacturers' frames in different sizes, I was surprised to find that most of the time the geo of a "size L" (or size XL) would be close to identical across most manufacturers - so you might end up with a not-fitting bike if you followed the wrong size calculator's advise.
While I am with Seth here that I don't buy in the trend to ever large reach, I seem to have a quite high tolerance for reach variation, so this wasn't the problem (but I am still a beginner so I might be blind to the differences). But what really was a practical limitation was seat tube length - on some bikes with long seat tubes, I had to insert the dropper almost all the way, in one instance we even had to consider switching to a dropper with a shorter drop.
I’m 6’ tall and 175mm are too big for me. My knees feel creaky/sore with them. First “upgrade” on my new bike was spending $200 to get 170mm cranks, and it feels so much more comfy! Btw: SuperBoost Plus is a pain in the a$$! Pivot sells their bikes with a custom OEM RaceFace crankset available only to them in 175mm, so needed an extra adapter (thus the high cost for swapping). Love this video!
Super boost is stupid and it annoys me to no end that Pivot is so enamored with it.
This is totally understandable in the evolution of bikes, when I built my bike a few years ago, I went through measurements extensively to try and get everything as perfect as possible. One thing I spent considerable time figuring out was crank length. I can't remember exactly what I went with, but I think was either 165 or 170 because for my height it made the most sense. As time goes on and technology improves it only makes sense to move with it. It seems like every year there's some new tech coming out and sometimes that tech is absolutely insane and isn't worth adopting, but sometimes?? you get something like this where the idea is sound and makes total sense.
Love your videos as always. Keep on riding and making cool stuff for us to watch.
Great video! Very informative. One aspect of smaller front chain rings that seldom gets a mention is the effect on chain life. The smaller the chain ring, the greater the leverage, so the more strain gets put on the chain. This may not be much of an issue for weekend warriors, but those who do expedition touring, dropping down from a 46 tooth chain ring of the good old days, to somewhere in the low 30s, means that you’re going to be buying chains (and front chain rings) more often.
having used shorter cranks before, honestly 170mm feels way better for me and I'm pretty happy to stick with them.
I also prefer longer cranks, going from 175 to 170 is feeling like I'm restricted, with less power.
The 8:33 rule 0.2 x leg length fits well in my case.
This is absolutely correct! I have been fighting for short cranks for more than 30 years .
As a short rider i now use 140mm cranks .
VERY well done video, and I learned more about crank geo in this vid than I have in my entire "riding life" since racing BMX in my early teens.
Currently building a new bikepacking rig and decided to run 170mm rather than the 175 I’ve always had. Time and miles will tell. Thanks Seth!
Seth: When I get ritch I wont tell anyone but there will be signs...
Buys 500$ cranks
Or 2x that for eeWings...
I'm 6'8" and just switched from 175mm 32T cranks to 165mm 30T cranks on both my mountain bikes. I did it to address knee pain on long climbs (it helped a ton!) but I was also amazed by how much of a difference it made on techy climbs. I can pedal through way more stuff now, and as a result I'm clearing more features than I have ever been able to. I feel like pedal clearance is actually more important on XXL bikes, since the wheelbase is so long that its easy for me to get high centered on everything. The crank length formula says I should be using 200mm cranks, but given the realities of BB height and wheelbase, I'd highly recommend short cranks even to my fellow giraffes.
I'm 67 but have a 38inch inseam so the formula said 200mm for me to and I just kinda figured that I'm already running on the short side on my xxl gen 6 fuel ex 8 at 170mm 30t interesting though
I've been tempted to give shorter cranks a go, but hearing they help with knee pain makes me want to get onto it faster.
I don't ride off road (I have an 80s Peugeot ATB frame that I have setup for road use) but about 18 months ago I blew out one of my knees from taking my BMX to a skate park and forgetting that i'm closer to my 40s than my 20s.... 100+kg of human landing on one knee on cement is not a great feeling...
While the majority of the damage healed up, I still have issues with it getting sore and seizing when my leg is bent on the upstroke.
Well done!!! Nice video. I bought a new 2023 Norco Fluid FS A1 medium frame this year which came with 175mm cranks. I love the bike but early on began having sore knees. After a little research I dropped to 165mm cranks and an oval 32t chain ring from 3P. The difference has been dramatic, and the chainring compensates for the reduced leverage. Thanks again for all your awesome content!
How tall are you? I got a medium FS A4 this year and I was wondering if I should change the cranks. I’m 5’6, and the bike feels a bit big, but the small felt a bit cramped.
@Jydmd Hi Jesse, I'm 5'10" . I was supposed to be on a large, according to Norco's website, but it was a little too big for the standover, so I went with a medium. No regrets. The shorter cranks did help. Jim
Great video. I found a couple of formulas online for crank length. Buying a kids bike I noticed that a lot of (especially box store) bikes come with far too long cranks. Better bike brands do seem to pay more attention. Details matter and this feeds back into spinning like on road bikes and road bikers are starting to gear like mountain bikes. So cool to think about.
I've been on 175mm cranks on trail/xsc mtb for 20+ years, 172.5mm on road for 5 years. Recently tried 165mm on my mtb and didn't like it. I felt like I lost too much power and had to make up for it with spinning which isn't great for the flattish terrain in central NC. For gravel riding I felt like the shorter cranks really slowed me down. If I had an enduro bike and did a lot of climbing I think the 165mm-170mm cranks would work well for me. I'm 5'11" with longer legs and shorter torso which contributes to liking 175mm cranks.
I'm your size and 170s work well for me. 165s feel too short for sure, 175s are fine but seem to start to hurt my hips on 4+ hour rides. My legs probably aren't as long as yours though
Im 6'1" and use the same setups. I tried 170 on my mtb and didnt like it. Felt less stable when standing and coasting downhill.
I’m 6’3” and I feel that the industry standard crank length of 170-175 is probably sub optimal because it’s too SHORT. It means I have to raise my saddle much higher, which affects how I ride the bike with my center of gravity being raised.
Longer cranks for me would allow me to run a shorter saddle height, which would make for a much more balanced riding position. It would also increase the likelihood of pedal strikes though, so the fix for that would be to change the frame geometry for taller riders such that the BB is raised comparing to smaller sizes.
If you’re in the top or bottom 20% of rider height, you’re in most cases buying a bike that has many, many sizing compromises. Some components are sized up/down, but not all. Wheel size, for instance only has two options, so even if you were able to customize the frame to each individual rider, the fact that you can’t do that with the wheels themselves means that you will still need to make other geometry compromises.
Yep. Just switched to 190mm on my "road" bike, and it's nice. Would be awful for pedal strikes off-road, though.
For us tall guys, probably higher BB, longer wheelbase (longer chainstays, if sticking with normal wheel sizes), and ideally much bigger tubes to compensate for what would be a very noodly frame once it's properly scaled.
The problem is that everyone markets low BB and short chainstays as features, even if they're throwing large-bike's balance right out the window.
Great video as always! My Nukeproof Scout has a low BB and came with 170mm cranks. I rarely get a pedal strike but I might consider going to 165s.
Recently went through all this with a new bike build. I was able to choose the cranks for my new bike even though it was a stock build (thank you, canfield!) And I went with 165mm which was actually longer than they said they typically stock on their size medium bikes. I am 5'9" with a 33inch inseam and the math would put me around 170 but I wanted to try the 165 anyway. The extra ground clearance vs my old 175 cranks is amazing, but im definitely dealing with some of the side effects you mentioned.
The bike came with a 32t chain ring and a 170mm dropper. I have probably at least 100mm of seat post showing and I even put the seat a little lower than id want for climbing. Not a ton of fun with the descents. Im honestly considering that goofy 240mm dropper because I just want the same butt to saddle clearance I had with a 210mm dropper and longer cranks on my other bike.
The 32t chainring is also making climbing a touch more strenuous but ill probably wait on sizing down on that for a bit.
As for sizing the cranks, I did come across some article saying overall leg length shouldn't affect your choice of cranks as much as the measurement from ankle to knee. That measurement actually did put me at a 165mm crank length suggestion even with my longer overall legs.
Where did you find this additional info?
I highly recommend an oval chainring with shortened cranks, makes initiating pedal strokes much easier if you're already losing leverage
I wondered why he didn't mention this option.
@@niclaskarlin honestly oval chainrings could probably be their own video
@@henrylarson8271 I'd watch that
I am interested in how much the crank length affects your position and feel on rough terrain, since you're changing the distance between your feet. We don't see enduro motorbikes with one foot forward and one back, just as snowbikes often have a single standing point (of course, unless they have a drivetrain). Does this mean that standing with your feet together is better? And if so, do shorter cranks help with that?
yes, standing with you feet together is absolutely better. Having pedals is the only reason to have your feet staggered
Been looking into this and I wish I found this video first it answered all my questions
Dude. I have been banging on about this exact same subject with literally exactly the same arguments as you make in this video since the 1990s !! Nobody listened with the answer always the same "bike companies know what they are doing". Hurrrah !! Somebody agrees with me finally. ... I will show this to all my peeps with the tag line "see, whaddiditellya". Made my day 😊
Day 2 of asking Seth to buy a tandem bike
he already has one?
He has one already
@@leopichler Really? I haven't seen it... Did he make a video about it?
Cringe
What's that??
NOTIFICATION GANG!!!!!!
I'm always entertained by your videos, and do usually learn something. I recently went from a 170 to a 160 last fall on a rebuild, and it feels like I raised the BB. It's a noticeable difference with fewer strikes over roots and rocks. Or maybe it's a placebo effect since I'm hyper-aware now. Either way, I'm happy with the change. I'm 5'-11" fwiw.
This is super comprehensive! Thanks so much.
The real question is: How come 100% of ALL "Are shorter cranks better" videos feature 5Dev cranks? Those boys sure know how to market themselves.
They also lowkey are a sponsor of mine LOL, but still, it's interesting to see that they own this space even though they are so small
They're one of the few manufacturers offering anything shorter than 165, and they've gone all-in on shorter cranks. I'm not sure how you'd do a video on short cranks without at least mentioning them.
My thoughts exactly. 5Dev seem to be the one driving this short crank craze so it’s a bit hard to take this seriously when someone’s like “I switched to short cranks!” *whips out 5Dev GX crank replica*
Hope, Canfield etc all make short cranks..
A higher saddle height (due to shorter cranks) is not necessarily an issue. It may allow you to run a longer dropper. You also completely ignored one important side effect of shorter cranks: that it effectively makes the bike smaller by bringing your feet closer together. This is a great benefit for short (or short-legged) riders who may have trouble with bike-body separation.
Great point, now I'm really sold.
I’m just getting into mountain biking, and it’s been a good bit since I did any type of bike riding, so I’ve really enjoyed your channel. Also being 5’3”, I appreciate the fact you know what it’s like to be short in this sport 😂
That was easy to follow. Happy holidays and a happy new year.
Recently tried 165mm cranks (I’m 6’2”) and it made a HUGE difference.
In what way?
He had to raise his seat 10mm at least to compensate?? This is what put me off changing once I’d looked into it in depth….I’m already high in my seated position at 6’1” and didn’t need my centre of gravity even higher for seated riding, which is what we end up doing most….you’ve also got a narrower foot base (with pedals fore and aft) and a higher position when off seat. I’m sticking with a very unfashionable 175mm!
That is a great point I had not thought about, it will raise the seat height.
To his credit, Seth does mention raising the seat as one of the downsides….very few online discussions seem to highlight this!
@@nigelroe8195 and even if you did have that tricky multi-length crankset to test the lengths out, it is sometimes hard to know completely in just a few rides. I recently went down from 175 to 170 but only because the new bike I purchased was having bad pedal strike.
Wouldn't it be better to measure your leg length below/above knee, look at biomechanical data for force per knee angle, and then optimize for a certain angle range?
it probably would be mr. fancypants
Maybe, but what if person 1 has longer upper thigh length than person 2, but both have equal length crus (knee to ankle)? Measuring from saddle point is just easier.
@@Dorkbike I looked it up, it seems to be called "femorotibial ratio" and varies between 1.15 and 1.4.
You'd just have to measure knee to ground as well, put both into a calculator app and get a suggestion for crank length.
the problem is that it's really tough to know where you should measure your femur. Even if it would be a more ideal way to measure, it's practically difficult to do. It's a common problem even with bike fitting, where they're measuring angles either via mocap, or goniometers, and it's remarkably difficult to know where to measure to and two different fitters can give enormously different measurements based on where they guess your joints are. Even if the mocap is a very precise measurement, the measurement point could be a couple cm too high or low at both ends, and read a massively different angle.
Really, you're just trying to get in the ballpark to know where to start, and it'll probably be a bit of trial and error to get it how you like it, so for most people the book in the crotch method's already a big improvement over just using their height.
Additionally, it takes some time to adapt to the changes, so even going to a "better" crank length might be slightly worse initially. or might improve, but only partially, and could require some time to get your muscle memory adjusted to it.
It's kind of a drag, because they're not a cheap thing to experiment with. I have long legs, and have stepped it up a bit over 2 bikes (180mm, and 190mm) and both have been an improvement, but who knows what would actually be "ideal" if I could try every different length for a month and see what I like most. Either way, I like the 190mm more than I liked the 175, so it's an improvement for now.
That was an amazing video. One of my favorites.
Thanks Seth for making such amazing videos
You should come ride in rhe bow valley, Canmore and Banff!!!! Lots of stuff close by!! Like golden, revelstoke, bragg creek...
Id be happy to show you around!!!
Thank you for the info! Seriously considering trying shorter cranks
"all their cranks are made by CNC and so they can make as many sizes as you want without altering the costs"... well, yes, because they're all gonna be stupid expensive, because they're made by CNC 😂
I went and looked at their website the cranks are basically $400 on up.
Cast and forged is stronger anyway
first!
Your first
nice video as always ! a contribution from my experience, for what it's worth :
I tend to see that optimal crank length also depends on your body type.
- if you're a long, lean person, you might benefit from shorter cranks relatively to your body size (as you said, because your cardiovascular system is probably more efficient than your muscular system).
- on the opposite end of the spectrum, if you have a muscular, burly body, it seems to benefit you to pedal harder with a lower cadence for the same speed (because it's exactly the opposite case). this also fits your personal preference for a bit longer cranks than the calculation indicated :)
thanks !
Just exceptional content. Thank you Seth.
Awesome detailed video about crank length. Thank!!!!!!
Thank you for being short, Seth. I can relate all too well with your struggles.
This video is absolutely brilliant, thank you!
I definitely learned something today mate, cheers!
Seth I am going to get my dream bike soon thank you for teaching me so much about mt biking😊